Gas turbine fuel system comprising fuel oil distribution control system, fuel oil purge system, purging air supply system and fuel nozzle wash system

ABSTRACT

Plurality of fuel nozzles X 1  and X 2  in combustor X are supplied with fuel gas from fuel gas system and fuel oil from fuel oil system, respectively. Gas turbine operation is done with fuel being changed over to either gas or oil. Fuel oil distribution control system A controls oil flowing into plurality of fuel pipings. When oil is changed over to gas, fuel oil purge system B is supplied with air of appropriate temperature and pressure from purging air supply system C. This air flows into fuel oil pipings and nozzles X 2  for purging residual oil therein. Fuel nozzle wash system D is supplied with water by-passing from wash water tank for compressor washing. This water flows through nozzles X 2  for washing thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a gas turbine fuel system andmore specifically to a gas turbine fuel system comprising a fuel oildistribution control system, a fuel oil purge system, a purging airsupply system and a fuel nozzle wash system in which fuel oildistribution is controlled to be done uniformly to a plurality of fuelnozzles with enhanced reliability of fuel distribution and residual oilin fuel pipings and nozzles when gas turbine operation is changed overto gas fuel from oil fuel is purged effectively so that load changecaused by burning of the residual oil at the time of purging isprevented.

2. Description of the Prior Art

FIG. 9 is a block diagram of an entire gas turbine fuel systemcomprising therein a fuel oil supply system, a fuel oil purge system, apurging air supply system and a compressor outlet wash system in theprior art. In FIG. 9, a combustor X comprises therein a plurality, about20 pieces for example, of fuel nozzles X₁, X₂ disposed along an innerperiphery thereof. The fuel nozzles X₁ are supplied with fuel gas from afuel gas supply system and the fuel nozzles X₂ are supplied with fueloil from a fuel oil supply system G. These gas and oil are changed overto either one thereof to be supplied into the combustor X forcombustion. The fuel oil supply system G, as mentioned, is a system forsupplying therethrough fuel oil and a fuel oil purge system H is asystem for purging oil remaining in the piping system or fuel nozzleswhen the fuel is changed over to gas from oil. A purging air supplysystem J supplies therethrough a purging air into the fuel oil purgesystem H. A compressor outlet wash system K is a system for injectingwater into a compressor outlet for washing this compressor outlet whichcommunicates with the combustor. Description will be made further oneach of the above systems.

The fuel oil supply system G will be described first. In the gasturbine, a stable combustion is required for a wide range of fuel flowrate from ignition to power output. Especially, in the low fuel flowrate range at the time of ignition etc., there is only a smalldifferential pressure of the fuel nozzles in the combustor, whichresults in an unstable combustion. In the recent gas turbine, there areprovided a large number of fuel nozzles of about 20 pieces and therearises unbalance in the fuel flow rate by the influence of headdifference between upper ones and lower ones of the fuel nozzles whichare disposed up and down. For this reason, a flow divider is provided sothat fuel is divided to be supplied uniformly to each of the fuelnozzles. But this flow divider is not necessarily of a sufficientreliability and thereby often caused are troubles in the fuel system.

FIG. 10 is a diagrammatic view of the fuel oil supply system G in theprior art. In FIG. 10, fuel oil is controlled of flow rate by a flowcontrol valve 11 to then flow through a piping 12 and enters a flowdivider 80 to be divided there to flow through a plurality of pipings 82of about 20 pieces and to be supplied into each of the fuel nozzles X₂of the combustor X. The gas turbine fuel nozzles X₂ are disposed inabout 20 pieces along a circumference and there is a head difference ofabout 4 m between the nozzles of upper position and those of lowerposition. This head difference produces unbalance in the fuel flow rate,especially in the low fuel flow rate range at the time of ignition. Forthis reason, the flow divider 80 is provided but this flow divider 80 isconstructed such that a spiral shaft is disposed in a cylindrical bodyand while this shaft is rotated, fuel oil is flown into the cylindricalbody to be divided to flow through each of the plurality of pipings 82uniformly. A motor 81 is operated only in the operation start time forensuring a smooth start of rotation of the flow divider 80.

FIG. 11 is a view showing relation between load transition (fuel flowrate) and system differential pressure in the prior art gas turbine,wherein as load increases, fuel flow rate increases from gas turbineignition time t₀ to rated speed (no load) arrival time t₁ and further totime t₂ when the system differential pressure including nozzledifferential pressure comes to a necessary nozzle differential pressureV₁. That is, during the time T from t₀ to t₂, the system differentialpressure does not reach the necessary nozzle differential pressure V₁but it reaches V₁ at time t₂ to increase more thereafter. Accordingly,the nozzle differential pressure is low during the time shown by T andif there is a head difference between said plurality of fuel nozzles,there occurs unbalance of fuel flow rate between each of the fuelnozzles, hence the flow divider 80 is operated so that the unbalance ofthe fuel oil between each of the fuel nozzles may be eliminated. Butthis flow divider 80 has a very small gap between the inner rotationalbody and the stationary portion for its function and this makes controlof foreign matters difficult and has been often causes of troubles inthe fuel system.

Next, the fuel oil purge system H will be described. FIG. 12 is adiagrammatic view of the fuel oil purge system in the prior art at thetime when the gas turbine fuel is changed over. In FIG. 12, numeral 1designates a flow control valve in a fuel gas system, numeral 2designates a piping therefor, numeral 3 designates a fuel gasdistributor, which distributes the fuel gas to the plurality of fuelnozzles X₁ and numeral 4 designates a plurality of pipings, which supplytherethrough the fuel gas from the fuel gas distributor 3 to therespective fuel nozzles X₁.

Numeral 11 designates a flow control valve in a fuel oil system, numeral12 designates a piping therefor, numeral 13 designates a header, whichdistributes the fuel oil from the piping 12 to the plurality of fuelnozzles X₂ and numeral 14 designates a plurality of pipings, which areconnected to the header 13 and supply therethrough the fuel oildistributed by the header 13 to the respective fuel nozzles X₂. Numeral26 designates a purging air system piping, numeral 25 designates anopening/closing valve, numeral 23 designates a drain valve piping andnumeral 24 designates an opening/closing valve therefor. Combustor Xcomprises therein the fuel nozzles X₁, X₂.

In the mentioned system so constructed, while the operation is done withthe fuel oil being burned, the fuel oil flowing through the flow controlvalve 11 and the piping 12 is distributed by the header 13 to flowthrough the plurality of pipings 14 to the respective fuel nozzles X₂.The fuel oil so distributed is injected into the combustor X from thefuel nozzles X₂ for combustion there.

When the operation is done with the fuel being changed over to gas fromoil, the flow control valve 11 is closed and the fuel gas is led insteadinto the piping 2 to be supplied to the fuel nozzles X₁ through the fuelgas distributor 3 and the piping 4. In this case, the previous fuel oilremains as it is in the pipings 12, 14 and this fuel oil, if left there,is carbonized to stick there with a fear to cause blockage of thepipings and nozzles. Hence, it is necessary to remove such residual oilwhen the fuel is changed over to gas.

Thus, the opening/closing valve 25 is opened so that purging air 40 isled into the piping 12 from the purging air system piping 26. Thepurging air 40 enters the header 13 through the piping 12 to then flowthrough the pipings 14 to the fuel nozzles X₂ to be blown into thecombustor X. Thereby, the fuel oil which remains in the piping 12,header 13, pipings 14 and fuel nozzles X₂ is all discharged into thecombustor X. This purging of the residual oil is done while theoperation is continued with the fuel gas being supplied and burned inthe combustor X. But there is a considerable quantity of such residualoil itself in the piping 12, header 13, pipings 14 and fuel nozzles X₂and also there are provided a large number of the fuel nozzles X₂ andsame number of the pipings 14 connected to the respective fuel nozzlesX₂. Accordingly, if the residual oil in these portions is all dischargedinto the combustor X and the operation is continued with the fuel gas sochanged over, then the fuel oil so discharged into the combustor X burnsso that the fuel increases beyond a planned supply value, which elevatescombustion temperature to cause a large load change. Hence, realizationof a fuel oil purge system which does not cause such a load change haslong been desired.

Next, the purging air supply system J will be described. In the recentgas turbine, there is realized an operation system wherein fuel ischanged over to gas from oil, as mentioned above. This operation systemcomprises therein both of fuel oil system and fuel gas system and it isnecessary to purge fuel pipings and nozzles on the side not used.Especially in the fuel oil system, oil remains in the pipings and, ifleft as it is, is carbonized to stick there and there is a fear ofblockage of the pipings and nozzles.

FIG. 13 is a diagrammatic view of the purging air supply system J in theprior art gas turbine. In FIG. 13, numeral 110 designates a gas turbine,numeral 42 designates a piping for taking out therethrough outlet air ofair compressor and numeral 90 designates an air cooler, which comprisestherein a multiplicity of tubes communicating with the piping 42.Numeral 91 designates a motor for rotating a fan 92 to thereby supplyair to the air cooler 90 and numeral 43 designates a piping connectingto outlet of the air cooler 90. Numeral 93 designates also a piping,which diverges from the piping 42 for obtaining air of the purge systemand numeral 94 designates a cooler using water 95 for cooling the airfrom the piping 93. Numeral 96 designates a piping connected to outletof the cooler 94, numeral 97 designates a drain separator, numeral 98designates a piping connected to outlet of the drain separator 97,numeral 53 designates a pressure elevation compressor and numeral 99designates a piping connected to outlet of the pressure elevationcompressor 53. Numeral 100 designates a cooling using water 101 forcooling the air which has been heated to a high temperature by pressureelevation at the pressure elevation compressor 53 to an appropriatetemperature as a fuel nozzle purging air. Numeral 48 designates a pipingfor supplying therethrough the air which has been cooled to theappropriate temperature as the purging air at the cooler 100.

In the mentioned system so constructed, the air of the compressor outletof about 400° C. is cooled at the air cooler 90 to about 200 to 250° C.to be supplied into the gas turbine 110 as a rotor cooling air throughthe piping 43, wherein a portion of the air of the compressor outletdiverges from the piping 42 and is led into the cooler 94 through thepiping 93 to be cooled to about 130° C. to be then sent to inlet of thepressure elevation compressor 53. This air is removed of drain by thedrain separator 97 disposed between the pipings 96 and 98. Then, the airis compressed to a predetermined pressure at the pressure elevationcompressor 53 and its temperature is also elevated to about 200° C. Thisair of about 200° C. is led into the cooler 100 through the piping 99 tobe cooled there to about 150° C. which is appropriate for the purgingand is then supplied to each of the fuel systems through the piping 48as the purging air.

Thus, in the purging air supply system, as the inlet temperature of thepressure elevation compressor 53 becomes high, there is provided thecooler 94 for cooling the compressor outlet air of about 400° C. toabout 100 to 130° C. Also, as the air, when compressed at the pressureelevation compressor 53, is heated to about 200° C., it is cooled againat the cooler 100 to about 150° C. In this kind of system, therefore,there are needed the coolers 94, 100 or the like, which requires largefacilities and spaces therefor. Hence, it has been needed to improvethese shortcomings and to attain cost reduction.

Next, the compressor outlet washing system K will be described. FIG. 14is a diagrammatic view of the compressor outlet wash system in the priorart. In FIG. 14, letter X designates a combustor, numeral 112 designatesa compressor outlet and numeral 113 designates a manifold fordistributing wash water in an annular form, as described later. Numeral114 designates a plurality of wash nozzles, which are provided alongperiphery of the manifold 113 for injecting therefrom wash water intothe compressor outlet 112. Numeral 11 designates a flow control valvefor fuel oil, numeral 12 designates a piping and numeral 13 designates aheader for distributing fuel into a plurality of fuel supply pipings 14.Fuel oil is supplied from the respective fuel supply pipings 14 to aplurality of fuel nozzles X₂.

Numeral 60 designates an air control valve for leading a high pressureair into a wash tank 62 via a piping 61. The wash tank 62 stores thereinthe wash water for washing interior of the compressor outlet 112.Numeral 63 designates an opening/closing valve, through which the washwater flows to be supplied into the manifold 113 via a piping 64. Thewash water supplied into the manifold 113 is injected from the pluralityof wash nozzles 114 into the surrounding area for washing the interiorof the compressor outlet 112. Numeral 65 designates an opening/closingvalve and numeral 66 designates a piping for supplying therethrough thewash water in a necessary quantity into the wash tank 62.

In the gas turbine compressor outlet wash system so constructed, whenthe compressor outlet 112 is to be washed, the air control valve 60 isopened and the high pressure air is led into the wash tank 62 via thepiping 61 so that interior of the wash tank 62 is pressurized. Then, theopening/closing valve 13 is opened and the wash water is supplied intothe manifold 113 via the piping 64. The wash water is injected from thewash nozzles 114 for washing the interior of the compressor outlet 112.

On the other hand, as for the gas turbine operation, fuel oil is ledinto the header 13 via the flow control valve 11 and the piping 12 to bedistributed there to flow into the plurality of fuel supply pipings 14uniformly and is then supplied into the respective fuel nozzles X₂ forcombustion.

In the recent gas turbine, there is developed a dual fuel system inwhich both fuel oil and fuel gas are usable and the fuel is changed overto gas from oil, or to oil from gas, as the case may be. In such asystem, if, for example, the operation done by oil is stopped or iscontinued with the fuel being changed over to gas from oil, the fuel oilremaining in the fuel pipings and nozzles is carbonized to stick thereand there arises a fear of blockage of the fuel pipings and nozzles.Thus, attempt is being done for providing large scale facilities bywhich the fuel pipings and nozzles are purged by air or the like. Butthese exclusive purging facilities require a large apparatus, which arenaturally undesirable from viewpoint of cost reduction.

SUMMARY OF THE INVENTION

In view of the problems in the prior art gas turbine fuel system, it isa principal object of the present invention to provide a gas turbinefuel system comprising a fuel oil supply system and a fuel gas supplysystem so that gas turbine operation may be done with fuel being changedover to either oil or gas and further comprising a control system inwhich fuel is distributed to each fuel piping of said fuel oil supplysystem uniformly in an appropriate flow rate and pressure as well as apurge system in which, while gas turbine operation is done with gasfuel, residual oil in said fuel oil supply system is purged effectivelyby air or water so that said residual oil may not be carbonized.

In order to provide said gas turbine fuel system, the present inventionhas objects to provide following first to fourth systems:

First one is a gas turbine fuel oil distribution control system in whicha control valve is employed instead of a flow divider, said controlvalve being constructed such that differential pressure of each fuelnozzle is elevated at the initial time of gas turbine operation, as wellas fuel oil is distributed so as to flow into each of fuel pipingsconnected to fuel nozzles as uniformly as possible so that unbalance infuel oil flow rate caused by head difference between each fuel nozzle isdissolved and unusual elevation of the differential pressure at the timeof high fuel flow rate is prevented.

Second one is a gas turbine fuel oil purge system in which, when gasturbine operation is done with fuel being changed over to gas from oiland residual oil in fuel pipings and nozzles is to be purged, quantityof the residual oil to be discharged into a combustor is made as smallas possible as well as the residual oil is purged securely to bedischarged.

Third one is a gas turbine fuel nozzle purging air supply system inwhich compressor outlet air of about 400° C. is cooled at a rotorcooling air cooler to an appropriate temperature to enter a pressureelevation compressor, thereby some of coolers are made unnecessary sothat construction of the purging air supply system is simplified,installation space thereof is reduced and cost of facilities is reduced.

Fourth one is a gas turbine fuel nozzle wash system in which existinggas turbine facilities may be used to be modified with a simpleconstruction so that, when fuel is changed over to gas from oil, fuelnozzles are washed by water and residual oil in the fuel nozzles iswashed out, resulting in contribution to cost reduction of the gasturbine plant.

In order to realize said objects, the present invention provides meansof following (1) to (5):

(1) A gas turbine fuel system comprising a fuel oil supply system forsupplying fuel oil to a plurality of fuel nozzles and a fuel gas supplysystem for supplying fuel gas to said plurality of fuel nozzles so thatgas turbine operation may be done with fuel being changed over to eitherone of oil and gas, characterized in further comprising a fuel oildistribution control system for controlling flow rate and pressure offuel oil in each of fuel pipings connecting to said fuel nozzles withina predetermined range by a control means provided in said fuel oilsupply system; a fuel oil purge system provided close to said fuelnozzles in said fuel oil supply system for purging residual oil in saidfuel oil supply system and fuel nozzles by air; a purging air supplysystem for supplying air to said fuel oil purge system; and a fuelnozzle wash system for supplying wash water to upstream side of saidfuel nozzles in said fuel oil supply system connected to said fuelnozzles.

In the invention of (1) above, the fuel oil distribution control systemcauses fuel oil to flow into the fuel oil supply system uniformly sothat unbalance in the fuel flow rate in each of the pipings is dissolvedand the fuel oil purge system purges effectively the residual oil in thefuel oil supply system and fuel nozzles so that the problem of pipingsbeing blocked by carbonization of the fuel oil is dissolved. Also, thepurging air supply system supplies air of appropriate temperature intothe purge system so that air supply to the purge system is ensured.Further, the fuel nozzle wash system purges the residual oil byinjecting water so that reliability of purging the residual oil isenhanced. Said air purge and water purge may be done by either of thembeing changed over to one from the other as the case may be.

(2) A gas turbine fuel oil distribution control system, characterized inthat there are provided a series control valve comprising a plurality ofvalves for controlling pressure loss in a fuel oil supply system so asto correspond to a plurality of fuel nozzles, each of said plurality ofvalves being driven controllably at same time with same opening; a driveunit for driving said series control valve; and a control unit forcontrolling said drive unit, and said control unit is inputted with asystem differential pressure signal and a load signal of said fuel oilsupply system to put out to said drive unit a signal to throttle saidseries control valve approximately to an intermediate opening while thesystem differential pressure is a predetermined low differentialpressure and a signal to open said series control valve fully for apredetermined time when said system differential pressure comes to apredetermined high differential pressure.

In the gas turbine fuel oil distribution control system of the inventionof (2) above, while the series control valve is controlled of theopening by the control unit and the drive unit, the control unit isinputted with differential pressure signal and load signal of the fueloil supply system or the fuel nozzles to put out to the drive unit asignal to throttle the series control valve approximately to anintermediate opening while the system differential pressure is apredetermined low differential pressure during the time from gas turbineignition to rated speed arrival. In the high fuel flow rate area, whenthe system differential pressure comes to a predetermined highdifferential pressure, a signal to open the series control valve fullyis put out to the drive unit.

Thus, the differential pressure each of the fuel nozzles is set to ahigher differential pressure than the necessary nozzle differentialpressure by the series control valve and the gas turbine operation isdone with the fuel oil being so controlled that unbalance in the fuelflow rate as so far occurred in the low fuel flow rate area is reduced,hence the prior art flow divider becomes unnecessary and reliability ofthe fuel oil distribution is enhanced.

(3) A gas turbine fuel oil purge system in a gas turbine fuel oil supplysystem comprising a plurality of fuel oil supply pipings for supplyingfuel oil to a plurality of fuel nozzles via a header; and a drain pipingconnected to said plurality of fuel oil supply pipings, characterized inthat there are provided a sealing connection pipe close to said fuelnozzles in each of said fuel oil supply pipings between said header andfuel nozzles; and a purging air supply piping for supplying air to eachsaid sealing connection pipe, and each said sealing connection pipecauses the air from said purging air supply piping to flow toward saidfuel nozzles as well as to flow into said fuel oil supply pipings on theopposite side of said fuel nozzles to be discharged from said drainpiping.

In the gas turbine fuel oil purge system of the invention of (3) above,the sealing connection pipe and the purging air supply piping areprovided close to the fuel nozzles in each of the fuel oil supplypipings and air from the sealing connection pipe is injected from eachof the fuel nozzles so that the residual oil only in the very shortpiping between the sealing connection pipe and each of the fuel nozzlesis discharged into the combustor. At the same time, the combustion gasin the combustor is prevented from flowing reversely into the fuel oilsupply pipings by the air injected from the fuel nozzles, hence the airso injected has a function of sealing as well.

At the same time of said sealing function, the air also flows from thesealing connection pipe into the fuel oil supply pipings on the oppositeside of the fuel nozzles and after flowing through the fuel oil supplypipings and the drain piping, it is discharged outside of the system. Bythis flow of air, all the residual oil in the fuel oil supply pipings isdischarged outside of the system from the drain piping. According to theinvention of (3) above, therefore, when the fuel is changed over to gasfrom oil and the residual oil in the pipings is to be purged, theresidual oil to be injected into the combustor is only the residual oilin the very short piping close to the fuel nozzles and other residualoil is discharged outside of the system from the drain piping, henceload change caused by burning of the residual oil is reduced.

(4) A gas turbine fuel nozzle purging air supply system in a gas turbineair system for supplying air, extracted from compressor outlet air andcooled at an air cooler, to a rotor as rotor cooling air as well as forsupplying air, diverging from said air extracted from compressor outletair and being elevated of pressure at a pressure elevation compressor,to be used as fuel nozzle purging air, characterized in that said aircooler comprises a first cooler and a second cooler, air cooled at saidfirst cooler is used for said rotor cooling air and air diverging fromthe air cooled at said first cooler is sent to said second cooler to becooled and then sent to said pressure elevation compressor.

In the gas turbine fuel nozzle purging air supply system of theinvention of (4) above, the air cooler comprises the first and secondcoolers and the air cooled at the first cooler is used as the rotorcooling air to be supplied for rotor cooling. Further, a portion of theair cooled at the first cooler diverges to enter the second cooler to becooled again, thus the compressor outlet air is cooled to a lowertemperature and is led into the pressure elevation compressor. When theair is compressed to a higher pressure at the pressure elevationcompressor, its temperature also is elevated, but as the air at thepressure elevation compressor inlet is cooled enough to the lowertemperature at the first and second coolers, even if it is elevated oftemperature, it can be used as the fuel nozzle purging air without beingcooled further.

In the prior art system, air extracted from the compressor outlet air iscooled at a separate cooler and is led into the pressure elevationcompressor to be compressed and thus to be elevated of temperature. Thisair so elevated of temperature is cooled again at another separatecooler to be adjusted to a lower temperature which is appropriate forthe purging air. In the prior art system, therefore, separate coolersare needed and large facilities and space therefor are required. But inthe invention of (4) above, the air cooler for the rotor cooling air ismade in two units which are used for cooling the purging air as well,separate coolers are not needed, facilities are simplified and costreduction is attained.

(5) A gas turbine fuel nozzle wash system in a gas turbine wash systemcomprising a fuel oil supply system for supplying fuel oil to fuelnozzles in a combustor; a compressor wash water supply system forsupplying wash water to a compressor which supplies compressed air tosaid combustor; and a wash water tank for supplying the wash water tosaid compressor wash water supply system, characterized in that thereare provided a wash water by-pass piping and an opening/closing valvebetween said fuel oil supply system and compressor wash water supplysystem and when said opening/closing valve is opened, the wash water issupplied to said fuel nozzles from said wash water tank via said fueloil supply system to be injected from said fuel nozzles so that saidfuel nozzles are washable.

In the gas turbine fuel nozzle wash system of the invention of (5)above, the wash water by-pass piping and the opening/closing valve areprovided between the existing fuel oil supply system and compressoroutlet wash system so that the wash water for compressor washing in thewash water tank is led into the fuel oil supply system. When the fuel ischanged over to gas from oil, the oil remains in the fuel nozzles and iscarbonized to stick there, which results in a fear of blockage of thefuel nozzles. Hence, when the fuel is changed over to gas, wash waterfor the compressor washing is led to the fuel nozzles via the wash waterby-pass piping and fuel oil supply system to be injected from the fuelnozzles, thus the fuel nozzles are washed and fear of blockage of thenozzles is cleared. Accordingly, the existing pipings are made use ofand wash water for the compressor washing is used for nozzle washing aswell, thereby facilities cost is reduced and washing of the fuel nozzleswith simple structure becomes possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an entire gas turbine fuel systemcomprising a fuel oil distribution control system, a fuel oil purgesystem, a purging air supply system and a fuel nozzle wash system of oneembodiment according to the present invention.

FIG. 2 is a diagrammatic view of the fuel oil distribution controlsystem of FIG. 1.

FIG. 3 is a view showing relation between load transition (fuel flowrate) and system differential pressure in the fuel oil distributioncontrol system of FIG. 1.

FIG. 4 is a diagrammatic view of the fuel oil purge system of FIG. 1.

FIG. 5 is a diagrammatic view of the purging air supply system of FIG.1.

FIG. 6 is a diagrammatic view of the fuel nozzle wash system of FIG. 1.

FIG. 7 is a diagrammatic view showing one application example of thefuel nozzle wash system of FIG. 6.

FIG. 8 is a diagrammatic view showing another application example of thefuel nozzle wash system of FIG. 6.

FIG. 9 is a block diagram of an entire gas turbine fuel systemcomprising a fuel oil supply system, a fuel oil purge system, a purgingair supply system and a compressor outlet wash system in the prior art.

FIG. 10 is a diagrammatic view of the fuel oil supply system of FIG. 9.

FIG. 11 is a view showing relation between load transition (fuel flowrate) and system differential pressure in the fuel oil supply system ofFIG. 9.

FIG. 12 is a diagrammatic view of the fuel oil purge system of FIG. 9.

FIG. 13 is a diagrammatic view of the purging air supply system of FIG.9.

FIG. 14 is a diagrammatic view of the compressor outlet wash system ofFIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Herebelow, description will be made concretely on embodiments accordingto the present invention with reference to figures. FIG. 1 is a blockdiagram of an entire gas turbine fuel system comprising therein a fueloil distribution control system, a fuel oil purge system, a purging airsupply system and a fuel nozzle wash system of one embodiment accordingto the present invention. FIG. 1 is a view of block diagram in contrastwith that in the prior art of FIG. 9.

In FIG. 1, there are provided in a combustor X a plurality of fuelnozzles X₁ and X₂, respectively, and like in the prior art, fuel nozzlesX₁ and supplied with fuel gas from a fuel gas supply system and fuelnozzles X₂ are supplied with fuel oil from a fuel oil supply system.Letter A designates a fuel oil distribution control system, whichcorresponds to the fuel oil supply system G of FIG. 9. Letter Bdesignates a fuel oil purge system, which corresponds to the fuel oilpurge system H of FIG. 9, letter C designates a purging air supplysystem, which corresponds to the purging air supply system J of FIG. 9,and letter D designates a fuel nozzle wash system, which corresponds tothe compressor outlet wash system K of FIG. 9. Letters E, F designatesselector valves, respectively, wherein in case of air purge, the valve Eis opened and the valve F is closed and in case of water purge, thevalve E is closed and the valve F is opened, reversely, and purging maybe done by either one of the air purge and the water purge or bycombination thereof in which the water purge is done first and then theair purge is done.

Description will be made below on each of the mentioned systems. FIG. 2is a diagrammatic view of the fuel oil distribution control system A ofFIG. 1, which is a view of the system in contrast with that in the priorart of FIG. 10. In FIG. 2, parts having same functions as those of theprior art shown in FIG. 10 are given same reference letters or numeralswith description thereon being omitted and characteristic portions ofthe present invention, that is, portions 10 to 14, 20 and 21, will bedescribed in detail.

In FIG. 2, numeral 13 designates a header and numeral 14 designates aplurality of pipings connecting to the header 13. Numeral 10 designatesa series control valve, which has a series of control valves in samenumber of pieces as that of the fuel nozzles X₂ so that each of thevalves is controlled at same time with same opening, that is, if thenumber of the fuel nozzles X₂ is 20 for example, the series controlvalve 10 is a 20 series control valve. While illustration of thestructure of the series control valve 10 is omitted, it is for examplesuch that each of the valves is linked by a link mechanism such as acylinder and opening of the valves is controlled simultaneously.

Numeral 21 designates a drive unit, which controls opening of the seriescontrol valve 10 simultaneously, as mentioned above, and comprises ahydraulic or pneumatic cylinder or an electromotive cylinder or thelike. Numeral 20 designates a control unit, which puts out an outputsignal to the drive unit 21 so that opening of the series control valve10 may be controlled, as described later.

In the construction as mentioned above, fuel oil passes through a flowcontrol valve 11 and a piping 12 to be led into the header 13 and isthen supplied into the respective pipings 14 whose number of pieces issame as that of the fuel nozzles X₂. The respective pipings 14 connectto the respective valves of the series control valve 10 and the fuel oilis supplied through the series control valve 10 and pipings 15 to therespective fuel nozzles X₂ for combustion in the combustor X.

The series control valve 10 is controlled of the valve opening via thedrive unit 21 by signal from the control unit 20, as described later,such that while a nozzle differential pressure is low, the opening isthrottled to an intermediate opening and when the nozzle differentialpressure increases in a high fuel flow rate area, the valve is openedfully to make flow resistance smaller, thus unusual elevation of thesystem differential pressure is prevented.

FIG. 3 is a view showing relation between load transition (fuel flowrate) and the system differential pressure in the fuel oil distributioncontrol system A of FIG. 2. In FIG. 3, while the system differentialpressure is lower than the necessary nozzle differential pressure V₁from time to when the gas turbine is ignited to time t₁ when it arrivesat rated speed (no load), the series control valve 10 is throttled to anintermediate opening so that the system differential pressure iselevated higher than the necessary nozzle differential pressure V₁,which is shown by broken line in FIG. 3, as fuel flow rate increases.

At the time t₁, the system differential pressure arrives at differentialpressure V₂ beyond which there may occur an unusually large differentialpressure. Then, the series control valve 10 is opened fully to make flowresistance smaller and the system differential pressure is reducedrapidly. Then, at time t₁′, the series control valve 10 is throttledagain to an intermediate opening. After the time t₁′, the systemdifferential pressure goes up again as the fuel flow rate increases andwhen it arrives at V₂, the series control valve 10 is opened fully againand thereafter same is repeated so that control is done.

The system differential pressures V₁, V₂ are set in the control unit 20to be stored and when the control unit 20 is inputted with gas turbineload signal and system differential pressure signal, it checks therespective system differential pressures at times t₀, t₁ and t₁′ in theload transition and when the ignition is done at t₀, signal to throttlethe opening of the series control valve 10 is put out to the drive unit21 so that the opening of the series control valve 10 is throttled to anintermediate level and when the system differential pressure comes toV₂, signal to open the series control valve 10 fully is put out to thedrive unit 21 so that the valve is opened completely and same control isrepeated thereafter.

According to the fuel oil distribution control system A as describedabove, opening of the series control valve 10 is controlled by thecontrol unit 20 and the drive unit 21 so that while the systemdifferential pressure is low for the time of low load after theignition, opening of the series control valve 10 is throttled to elevatethe system differential pressure and unbalance in the fuel flow rate dueto head difference of the fuel nozzles is dissolved thereby and in thehigh fuel flow rate area, the valve is opened fully and unusualelevation of the system differential pressure is prevented thereby.Thus, there is needed no such a flow divider as in the prior art, fueloil flow unbalance between each of the fuel nozzles is preventedsecurely and reliability is enhanced.

Next, the fuel oil purge system B will be described with reference toFIG. 4. In FIG. 4, parts shown by reference numerals or letters 1 to 4,11 to 14, 23, X, X₁ and X₂ are same as those in the prior art shown inFIG. 12 with description thereon being omitted and characteristicportions of the present invention, that is, parts shown by referencenumerals 30 to 33, will be described in detail.

In FIG. 4, numeral 30 designates a purging air system piping, numeral 31designates an opening/closing valve, numeral 32 designates a pluralityof sealing connection pipes and numeral 33 designates a plurality ofpipings. Each of the pipings 33 connects at its one end to each of thefuel nozzles X₂ and at its the other end to each of the sealingconnection pipes 32 and length of each of the pipings 33 is made asshorter as possible preferably. Also, each of the sealing connectionpipes 32 is a T type connection pipe which comprises ports connecting tothe pipings 14 and 33 and the purging air system piping 30,respectively.

Thus, the purging air system piping 30 is connected closer to the fuelnozzles X₂, as compared with the prior art purging air system piping 26,between the header 13 and the fuel nozzles X₂, hence residual oil in thepipings to be discharged into the combustor X is reduced, as describedlater.

In the fuel oil purge system B constructed as above, while operation isdone by fuel oil, the fuel oil passes through the flow control valve 11and the piping 12 to enter the header 13 and is distributed there toflow through the plurality of pipings 14 and the sealing connectionpipes 32 to be then supplied into the plurality of fuel nozzles X₂ viathe pipings 33 and is injected into the combustor X for combustion.

When operation is to be done with the fuel being changed over to gasfrom oil, the flow control valve 11 is closed and fuel gas is suppliedinstead through the flow control valve 1, piping 2, fuel gas distributor3 and piping 4 to enter the respective fuel nozzles X₁ to be burned inthe combustor X. In this case, there remains the previous fuel oil inthe piping 12, header 13, piping 14 and piping 33 and if this remainingfuel oil is left there as it is, it is carbonized to stick there, thuswhen the fuel oil has been stopped to be changed over to fuel gas, it isnecessary to purge the remaining fuel oil while operation is being doneby the fuel gas.

In case of the purging, the opening/closing valve 31 is opened first sothat purging air 41 is led into the purging air system piping 30 to flowthrough one end each of the sealing connection pipes 32 and the piping33 to enter the fuel nozzles X₂ and is then injected into the combustorX from the fuel nozzles to be burned. At same time, the purging air 41is also flown into the piping 14 through the other end each of thesealing connection pipes 32.

Further, the opening/closing valve 24 is also opened to communicate withthe drain valve piping 23. Thus, the purging air 41 passes through thepurging air system 30, sealing connection pipes 32 and pipings 14 andfurther through the header 13, piping 12, opening/closing valve 24 anddrain valve piping 23 and is discharged outside. By said flow of thepurging air 41, the fuel oil remaining in the pipings 33 is dischargedinto the combustor X and the fuel oil remaining in the pipings 14,header 13 and piping 12 on the opposite side is discharged outside ofthe system via the drain valve piping 23.

When the purging of the residual oil is to be done while the operationis being done with fuel gas, as the purging air 41 from the purging airsystem piping 30 flows through said one end each of the sealingconnection pipes 32 toward the combustor X to be injected from the fuelnozzles X₂, the purging air 41 has a sealing function to prevent reverseflow of the combustion gas from the combustor X and in addition to thissealing function, the purging air 41 causes the residual oil in thepipings 14, header 13 and piping 12 on the opposite side of the sealingconnection pipes 32 to be discharged outside of the system from thedrain valve piping 23.

In the prior art case shown in FIG. 12, if the opening/closing valve 24of the drain valve piping 23 is opened during the operation, there mayarise a case that the combustion gas from the combustor X is sucked toflow reversely through the pipings 14, header 13 and piping 12 so thatthe residual oil in the pipings may burn by the high temperaturecombustion gas to damage the pipings, but in the system of the presentinvention, the purging air 41 is flown from the sealing connection pipes32 toward the combustor X to be injected from the fuel nozzles X₂ so asto seal the combustion gas, thus the shortcomings in the prior art isprevented.

According to the fuel oil purge system B as described above, theconstruction is made such that the purging air system piping 30 and thesealing connection pipes 32 are connected closer to the fuel nozzles X₂between the pipings 14 and the fuel nozzles X₂ and the purging air 41having the sealing function as well is injected from the fuel nozzles X₂so that the residual oil in the pipings 33 is discharged as well as thecombustion gas from the combustor X is prevented from flowing reverselyinto the pipings 14 side.

Further, the purging air 41 from the sealing connection pipes 32 isflown through the pipings 14, header 13 and piping 12 to be dischargedfrom the drain valve piping 23 so that the residual oil in these pipingsis discharged outside of the system from the drain valve piping 23, thuswhen the fuel is changed over to gas from oil and residual oil in thepipings is to be purged, the residual oil to be discharged into thecombustor X is only that remaining in the short pipings 33, thereby loadchange caused by combustion of the residual oil is reduced and a largeload change is prevented.

Next, the purging air supply system C will be described with referenceto FIG. 5. In FIG. 5, parts shown by reference numerals 110, 42, 43, 48and 53 are same as those in the prior art shown in FIG. 13 withdescription thereon being omitted and characteristic portions of thepresent invention, that is, air coolers shown by reference numerals 50,51 and pipings thereof as well as simplified system accompaniedtherewith, will be described in detail.

In FIG. 5, numeral 50 designates a first air cooler and numeral 51designates a second air cooler. Both of the air coolers 50, 51 arecooled by air sent from a fan 45 driven by a motor 44. In these aircoolers 50, 51, compressor outlet air is led into the first air cooler50 via the piping 42 and the air after cooled is led from outlet of thefirst air cooler 50 into the gas turbine 110 as rotor cooling air viathe piping 43. At same time, a portion of the air at the outlet of thefirst air cooler 50 is extracted to be led into the second air cooler 51via a piping 49.

The air cooled at the second air cooler 51 is led into a drain separator52 via a piping 46 to be removed of drain and is then led into thepressure elevation compressor 53 via a piping 47 to be elevated ofpressure and thereby to be heated to an appropriate temperature aspurging air. Thus, this air is supplied as fuel nozzle purging air viathe piping 48.

In the purging air supply system C constructed as above, the compressoroutlet air is of about 400° C. and is led into the first air cooler 50via the piping 42 to be cooled to about 200 to 250° C. by air sent fromthe fan 45 and is then supplied into the gas turbine 110 as the rotorcooling air like in the prior art.

The air cooled at the first air cooler 50 is of about 200 to 250° C. anda portion thereof diverges into the piping 49 to enter the second aircooler 51. The air entering the second air cooler 51 is cooled, like inthe first air cooler 50, by air from the fan 45 driven by the motor 44.The air so cooled is of about 60 to 80° C. and is led into the drainseparator 52 via the piping 46 to be removed of drain and then entersthe pressure elevation compressor 53 via the piping 47 to be elevated ofpressure and thereby to be elevated of temperature to about 100 to 130°C. This air of about 100 to 130° C. is supplied to be used as the fuelnozzle purging air via the piping 48.

According to the purging air supply system C described above, the aircooler for obtaining the rotor cooling air is constructed in two unitsof the first air cooler 50 and the second air cooler 51 and thecompressor outlet air of about 400° C. is cooled to about 200 to 250° C.at the first air cooler 50 to be used as the rotor cooling air. At thesecond air cooler 51, the air so cooled to about 200 to 250° C. isfurther cooled to about 60 to 80° C.

The air so cooled to about 60 to 80° C. is used as inlet air of thepressure elevation compressor, hence the air after elevated of pressureis of temperature of about 100 to 130° C. which is appropriate as thefuel nozzle purging air. In the prior art case as shown in FIG. 13, theair entering the pressure elevation compressor 53, which is thecompressor outlet air, is of a high temperature of about 400° C., henceit is cooled as first step to about 130° C. at the cooler 94 and it iselevated of pressure at the pressure elevation compressor 53. But thisair is thereby elevated of temperature to about 200° C., hence it iscooled again at the cooler 100 for obtaining air of about 150° C.

For this purpose, there are needed the coolers 94, 100 which are largefacilities. But in the purging air supply system C of the presentinvention, the air cooler is made in two units of the first air cooler50 for obtaining the rotor cooling air and the second air cooler 51 forobtaining the fuel nozzle purging air, thereby the coolers 94, 100become unnecessary, which results in simplification of facilities,reduction of installation space and reduction of cost.

Finally, the fuel nozzle wash system D will be described with referenceto FIGS. 6 to 8. In FIGS. 6 to 8, same parts as those in the prior artshown in FIG. 14 are given same reference numerals or letters withdescription thereon being omitted and characteristic portions of thepresent invention, that is, portions shown by reference numerals 71 to75, will be described in detail.

In FIG. 6, numeral 71 designates a by-pass piping, which connects to theupstream side of the opening/closing valve 63 so that wash water fromthe wash tank 62 flows therethrough to by-pass. Numeral 72 designates anopening/closing valve and numeral 73 designates a header fordistributing the wash water. Numeral 74 designates a plurality of washwater supply pipings and numeral 75 designates a plurality of connectionpipes which are connected to the respective fuel supply pipings 14.

The wash water led from the wash water tank 62 into the header 73 viathe by-pass piping 71 is distributed to flow into the respective washwater supply pipings 74 and to further flow into the respective fuelsupply pipings 14 via the connection pipes 75 and then enters therespective fuel nozzles X₂.

In the fuel nozzle wash system D constructed as above, when the fuelnozzles X₂ are to be washed, the flow control valve 11 is closed, theopening/closing valve 63 is also closed, the opening/closing valve 72 isopened and the air control valve 60 is opened. Thus, high pressure airis led into the wash water tank 62 to pressurize the wash water in thetank so that the wash water is led into the header 13.

The wash water is distributed at the header 13 to flow into therespective wash water supply pipings and further to flow into therespective fuel supply pipings 14 via the connection pipes 75 and isthen injected into the combustor X from the respective fuel nozzles sothat residual oil in the fuel nozzles X₂ is washed and removed. Thewater containing the residual oil injected from the fuel nozzles X₂ isso discharged into the combustor X and is vaporized by the hightemperature there.

FIG. 7 is a diagrammatic view showing one application example of thefuel nozzle wash system D of the present invention. In FIG. 7, what isdifferent from that shown in FIG. 6 is that the by-pass piping does notdiverge from the piping 64 of the compressor wash system but isconnected directly to the wash water tank 62 and the opening/closingvalve 72 is provided in this by-pass piping 67, so that the fuel nozzlewash system is made in a separate system from the compressor washsystem. Construction of other portions of FIG. 7 is same as that of FIG.6. In the application example shown in FIG. 7 also, same function andeffect of the invention as those of the wash system shown in FIG. 6 canbe obtained.

FIG. 8 is a diagrammatic view showing another application example of thefuel nozzle wash system D of the present invention. In FIG. 8, what isdifferent from that shown in FIG. 6 is that the by-pass piping isconnected to the downstream side of the opening/closing valve 63 of thecompressor wash system. In this system of FIG. 8, the compressor washsystem and the fuel nozzle wash system are operated at same time by thesingle opening/closing valve 63, wherein the opening/closing valve 72shown in FIGS. 6 and 7 is eliminated. Construction of other portions ofFIG. 8 is same as that of FIGS. 6 and 7. In the application exampleshown in FIG. 8 also, same function and effect of the invention as thoseof the wash system shown in FIGS. 6 and 7 can be obtained.

According to the fuel nozzle wash systems D shown in FIGS. 6 and 7, theconstruction is made such that there are provided the by-pass pipings71, 67 for flowing therethrough the wash water from the wash water tank62 of the compressor outlet wash system to by-pass and the wash waterflows through the header 73, wash water supply pipings 74 and connectionpipes 75 to the respective fuel supply pipings 14 and is then suppliedinto the fuel nozzles X₂ for washing the residual oil in the fuelnozzles X₂. Also, according to the fuel nozzle wash system D shown inFIG. 8, the construction is made such that the piping 64 of thecompressor outlet wash system and the piping 68 of the fuel nozzle washsystem are connected to the wash water tank 62 via the singleopening/closing valve 63. Thus, by these constructions, washing of thefuel nozzles X₂ can be done by the wash water from the wash water tank62 of the compressor outlet wash system and there is needed no exclusivewash apparatus of the fuel nozzles X₂, hence the wash system can be madein a simple piping structure, which contributes to cost reduction of thegas turbine plant.

It is understood that the invention is not limited to the particularconstruction and arrangement herein illustrated and described butembraces such modified forms thereof as come within the scope of theappended claims.

What is claimed is:
 1. A gas turbine fuel nozzle wash system in a gasturbine wash system comprising a fuel oil supply system for supplyingfuel oil to fuel nozzles in a combustor; a compressor wash water supplysystem for supplying wash water to a compressor which suppliescompressed air to said combustor; and a wash water tank for supplyingthe wash water to said compressor wash water supply system, whereinthere are provided a wash water by-pass piping and an opening/closingvalve between said fuel oil supply system and compressor wash watersupply system and when said opening/closing valve is opened, the washwater is supplied to said fuel nozzles from said wash water tank viasaid fuel oil supply system to be injected from said fuel nozzles sothat said fuel nozzles are washable.